US3704403A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power supply circuit to simultaneously vary frequency and amplitude in a motor speed control
Assignee: GEC AUTOMATION PROJECTS Inc
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Filing: 1972-02-23
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Granted: 1972-11-28
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Expires: 1992-02-23
Abstract
Abstract A multiple pulse pulse-width modulation system is disclosed for controlling the speed of a standard three-phase induction motor or synchronous motor. An oscillator provides a clock signal which is divided down by a counting chain of two flip-flops to provide a first signal which is half the frequency of the clock signal and a second signal which is a quarter of the frequency of the clock signal. The first signal is integrated over the half cycles thereof while the second signal is applied to a digital wave form synthesizer which includes shift register stages and weighting resistors. The wave form synthesizer provides three output signals which are a stepwise approximation to a three-phase sine wave. Each of the three phases of the three-phase sine wave are applied to a differential comparator for comparison with the output of the integrator. The oscillator is variable in frequency so that the frequency of the three-phase sine wave and the amplitude of the integrator output can be varied thereby.
Inventors
- 👤 Jimmie Douglas Gillett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:07
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/04; H02P27/06; H02P27/08; H02P27/047
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
146 words
A system for generating a plurality of drive signals for a multi-phase switching bridge; said system including: first means responsive to a periodically recurring clock signal for providing a periodic wave form having a predetermined wave shape and a peak amplitude dependent upon the period of occurrence of said clock signal; second means responsive to said clock signal for digitally synthesizing a plurality of phase signals having a fixed phase relationship therebetween; said second means generating one phase signal for each phase of said multi-phase switching bridge; each of said plurality of phase signals having a predetermined peak amplitude and a repetition frequency dependent upon the period of occurrence of said clock signal; and third means for individually comparing the instantaneous amplitude of said periodic wave form with the instantaneous amplitude of each of said plurality of phase signals to provide said plurality of drive signals.
Claim 2
Independent Claim
146 words
A system for generating a plurality of drive signals for a multi-phase switching bridge; said system including: first means responsive to a periodically recurring clock signal for providing a periodic wave form having a predetermined wave shape and a peak amplitude dependent upon the period of occurrence of said clock signal; second means responsive to said clock signal for digitally synthesizing a plurality of phase signals having a fixed phase relationship therebetween; said second means generating one phase signal for each phase of said multi-phase switching bridge; each of said plurality of phase signals having a predetermined peak amplitude and a repetition frequency dependent upon the period of occurrence of said clock signal; and third means for individually comparing the instantaneous amplitude of said periodic wave form with the instantaneous amplitude of each of said plurality of phase signals to provide said plurality of drive signals.
Claim 3
Dependent Claim
37 words
The system as defined in claim 1 in which said first means is an integrator for providing a triangular wave form whose instantaneous amplitude varies linearly as a function of time between occurrences of said clock signal.
Claim 4
Dependent Claim
27 words
The system as defined in claim 2 also including: means for dividing said clock signal, said means for applying said divided clock signal to said second means.
Claim 5
Dependent Claim
47 words
The system as defined in claim 2 in which said second means includes: counting means responsive to said clock signal for providing a plurality of timing signals; and a plurality of weighting networks responsive to said plurality of tiny signals for generating said plurality of phase signals.
Claim 6
Dependent Claim
18 words
The system as defined in claim 4 also including a variable frequency oscillator to provide said clock signal.
Claim 7
Dependent Claim
22 words
The system as defined in claim 4 in which said counting means is a shift register arranged as a ring counter circuit.
Claim 8
Dependent Claim
19 words
The system as defined in claim 1 also including said multi-phase switching bridge for providing three-phase motor drive signals.
Claim 9
Dependent Claim
25 words
The system as defined in claim 7 also including: a three-phase motor; and means for applying said three-phase motor drive signals to said three-phase motor.
Claim 10
Dependent Claim
37 words
The system as defined in claim 8 in which said first mean is an integrator for providing a triangular wave form whose instantaneous amplitude varies linearly as a function of time between occurrences of said clock signal.
Claim 11
Dependent Claim
47 words
The system as defined in claim 9 in which said second means includes: counting means responsive to said clock signal for providing a plurality of timing signals; and a plurality of weighting networks responsive to said plurality of tiny signals for generating said plurality of phase signals.
Claim 12
Dependent Claim
22 words
The system as defined in claim 10 in which said counting means is a shift register arranged as a ring counter circuit.
Claim 13
Dependent Claim
40 words
The system as defined in claim 11 also including: means for dividing said clock signal to which said first means is responsive to provide a divided clock signal, said means for applying said divided clock signal to said second means.
Claim 14
Dependent Claim
18 words
The system as defined in claim 12 also including a variable frequency oscillator to provide said clock signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-11-28 | 1976-05-29 | 1976-11-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-28 | 1980-05-29 | 1980-11-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-28 | 1984-05-29 | 1984-11-28 | $7700.00 | Window Closed / Lapsed |